System losing pressure

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Old 02-13-13, 04:51 PM
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System losing pressure

Tim is back with more problems. The system keeps losing pressure and the pump starts about every five minutes when the pressure drops to 40psi and shuts off @ 70psi. I have turned all faucets and toilets off. When the pump starts you can here a gush of water through the pipes. I've isolated the pump with a shut off valve and it holds the pressure not goes back to the holding tank. There are no leaking water pipes in the house. I just replaced the water reducing valve, expansion tank and bleed the lines. The heat is working fine. Any suggestions on what to try?
 
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Old 02-13-13, 05:50 PM
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I'm guessing this is a well and you posted it in the Heating systems by accident.

Is this a deep well or a jet pump (shallow) well ?

If you are able to shut the water off with a valve between the well system and the house. I would say it sounds like you have a problem with the check valve that keeps the water from draining back into the well.
 
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Old 02-13-13, 05:52 PM
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Tim, I'm a bit confused...

The system keeps losing pressure and the pump starts about every five minutes when the pressure drops to 40psi and shuts off @ 70psi
You are talking about a POTABLE WELL SYSTEM, aren't you? NOT the boiler system... correct?

You need to know that there is no connection between the domestic water system and the boiler system other than the single connection that feeds water into the boiler. They operate independently.

So, I am probably going to move your question to the water well forum once you confirm this to be the case.
 
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Old 02-13-13, 06:11 PM
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I have a well with a submersible pump which pumps water into a 165gallon tank, From there another pump pushes water through house. That secondary pumps keeps running as the system seems to keep losing pressure. Does the backflow valve on the boiler system maintain the pressure in the boiler? When boiler runs it appears to keep the pressure up in the system, once boiler stops the pressure goes down and the pump starts. (This is with all water usage shut off)
 
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Old 02-13-13, 06:16 PM
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once boiler stops the pressure goes down and the pump starts.
Something strange is going on there. The boiler only uses an extremely small and limited amount of water. It doesn't require a constant refill. The back flow preventer keeps boiler water from leaving the boiler and mixing with drinking water.

It sounds more like a leaking check valve in your second pump system. Nothing to do with boiler.
 
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Old 02-13-13, 06:25 PM
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I have a shut off valve on the line from the pump before water gets into boiler system. With that valve shut off the pump stay off and the pressure on the pump shows 70psi. The only time pressure stay up is when boiler is running.
 
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Old 02-13-13, 06:33 PM
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Where can that water possibly be going ?
If you are saying that the boiler is using that much water.......it must be coming out somewhere.

What is the pressure gauge on the boiler saying ?
 
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Old 02-13-13, 06:47 PM
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Thats what's so confusing. I've tried to isolate zones to find out where the water could be going but no luck. The pressure gauge on the boiler reads 20 but then starts losing pressure very slowly when not running then when it get below 20 the pump will kick in.
 
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Old 02-13-13, 07:13 PM
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Does the backflow valve on the boiler system maintain the pressure in the boiler? When boiler runs it appears to keep the pressure up in the system, once boiler stops the pressure goes down and the pump starts.
Tim, this just isn't making sense...

I understand the holding tank. I believe that's there because you have a 'low yield' well. The well probably can't keep up with the usage from the house therefore the tank acts as a 'buffer'.

The second pump is what provide the water pressure for the home...

BUT, the backflow preventer between the domestic system and the boiler only does what it's name implies, it prevents backflow of the nasty boiler water back into the domestic plumbing.

I think it's coincidence that you seem to have 'timed' the pressure loss in the home with the boiler running/stopping.

In order to verify this, temporarily CLOSE the MANUAL SHUT OFF between the boiler and the domestic system in order to prove that there is no relationship between the domestic pump running and the boiler running.

What I believe that you may find the problem to be is the CHECK VALVE between your 165G storage tank and the domestic pump drawing from it is leaking through.
 
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Old 02-13-13, 07:20 PM
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The pressure gauge on the boiler reads 20 but then starts losing pressure very slowly when not running then when it get below 20 the pump will kick in.
OK, maybe I'm gonna change my story after reading this...

Still, what I want you to do is close that manual shutoff valve between domestic and boiler.

If it is your boiler system that is losing water, the pressure will continue to fall in the boiler, but the domestic pump will not be influenced by it.

Closing a zone valve won't help you isolate a leak...

First of all, zone valves can't be relied on to close 100% water tight.

Second and more importantly is that closing a zone valve will only close ONE END of the pipe... the other end of that pipe is still open to the rest of the system. In order to isolate a leaking pipe, one would have to be able to close BOTH ends of the pipe.
 
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Old 02-14-13, 09:46 AM
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I've shut off the water going into boiler and pump works fine. When I run the tap the pump turns on and stops when I close the tap. Also maintains constant pressure (about 70psi). When I open the shutoff to the boiler the pump start pumping water hits 70psi, shuts off and immediately losses pressure until it hit 20psi then kick back on. It does this continously so basically the pump is continuosly running. I don't know where the additional water is going. There are no leaks in the entire system including the boiler. The boiler pressure is around 20psi. At that pressure is it enough to force the water back through the pump to the holding tank? I really don't see how that could happen, but?????
 
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Old 02-14-13, 09:50 AM
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Tim, I hate to say this but whether or not you can see a leak in the heating system, it sounds as if you have one... somewhere...

If you leave the water supply to the boiler turned OFF, will the boiler pressure eventually drop to ZERO on the boiler pressure gauge?
 
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Old 02-14-13, 10:02 AM
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leak

Maybe a leak in a radiant loop in concrete slab?

Steve
 
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Old 02-14-13, 10:08 AM
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No, it stayed at 20psi. If the pipes had a leak in the slab wouldn't the water seep from where the pipes go in or come out?
 
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Old 02-14-13, 10:18 AM
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No, it stayed at 20psi.
This isn't making any sense at all to me Tim...

I suspect that your boiler gauge is 'stuck' at 20. Have you EVER seen it below 20?

If the pipes had a leak in the slab wouldn't the water seep from where the pipes go in or come out?
Not necessarily. It would depend on 1) where the leak was in relation to where the pipes enter/exit; 2) the porosity of what ever is UNDER the slab. If the water can soak into the ground UNDER the slab, what motivation would it have to fight gravity and seep UPWARD?
 
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Old 02-14-13, 10:32 AM
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Sorry, I closed both shutoffs so the water in the boiler was isolated. I really don't want to ask this one, but short of jacking up the slab is there any alternatives?
 
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Old 02-14-13, 03:17 PM
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short of jacking up the slab is there any alternatives?
Not that I know of... is there any way possible that you might be able to abandon the pipes in the slab and run some new pipes where they need to go, but above ground? Maybe PEX tubing?
 
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Old 02-14-13, 08:40 PM
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You were right on. There is a leak in the heating line in the slab. I can't believe they allow builders to run pipes that way. Looks like my resolution is cut a six foot long trench under the carpet from the livingroom unit (which is still hot) to reach under the steps to the unit in the kitchen (which is cold) and add new line using pex. I think I've got my work cut out for me. HA! HA!
Thanks again for your help.
tim
 
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